HEAD TRAUMA

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Head and Brain Trauma • ~ 4 million head injuries in US per year. • ~ 450, 000 require hospitalization. – Most are minor injuries. – Major head injury most common cause of trauma deaths in trauma centers (>50%).

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Head and Brain Trauma • Leading cause of death and disability from birth to age 44. • Cause of death in 25% of trauma patients. • Cause of death in half of fatality MVCs. • Significant long term disability. • Prompt recognition and treatment can improve outcome. 3

Head and Brain Trauma • Every year, 142,000 Americans are killed as the result of head injury and another 50,000 – 70,000 are severely disabled. • Almost 30% of all childhood injury deaths result from a head injury.

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Causes of Head Injury • • • • •

MVC 50% Falls 21% Assaults and Violence 12% Sports and Recreation 10% Other 7%

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Head and Brain Trauma • Risk Groups – Highest risk, males 15 - 24 yrs of age. – Very young children from 6 months to 2 years of age. – Young school age children. – Elderly.

• As EMS providers, what can we do in our communities to reduce the incidence of head injuries? 6

Lecture Overview • Review the anatomy of skull and brain. • Discuss the pathophysiology of head injury. • Review of specific head injuries. • Describe the assessment of head trauma and the head injured patient. • Outline treatment strategies and describe the management of head trauma. 7

Skull Anatomy Review • Cranium – Double layer of solid (flat) bone which surrounds a spongy middle layer. – Frontal, occipital, temporal, parietal, sphenoid, and ethmoid bones form the cranium.

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Skull Anatomy Review • Noteable Features of the Cranium: – Middle meningeal artery. • • •

Important feature due to potential for injury. Lies under temporal bone. Common source of an epidural hematoma secondary to a blow to the temporal region.

– Foramen magnum. • Only opening of significant size in the cranium. (There are smaller openings for blood vessels, the auditory canal, etc.) • As pressure inside the cranial vault increases, pressure is applied to brain tissue as contents are pushed toward the opening. 9

Skull Anatomy

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Fontanelles

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Fontanelles The anterior fontanelle usually is closed by 14 months. The posterior and lateral fontanelles will usually close by 2 to 3 months after birth. A bulging fontanelle may indicate increased intracranial pressure, whereas a sunken or depressed fontanelle may be due to dehydration.

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Facial Bones Ethmoid bone Lacrimal bone Nasal bone Zygomatic bone Maxilla Mandible Vomer Inferior nasal concha Palatine 14

Anatomy

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Brain Anatomy The brain occupies 80% of intracranial space and weighs about 1600 grams or about 3.5 pounds. • Cerebrum – – – –

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Frontal lobe Parietal lobe Occipital lobe Temporal lobe

Cerebellum Medulla Pons Midbrain Diencephalon 16

Brain Anatomy Review • Cerebrum – Cortex • Voluntary skeletal movement • Level of awareness

– Frontal lobe • Personality

– Parietal lobe • Somatic sensory input • Memory • Emotions 17

Brain Anatomy Review • Cerebrum – Temporal lobe • Speech center • Long term memory • Taste • Smell

– Occipital lobe • Origin of optic nerve

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Hemoculus

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Brain Anatomy Review • Hypothalamus – Center for vomiting, regulation of body temp and water. – Sleep-cycle control. – Appetite.

• Thalamus – Emotions and alerting or arousal mechanisms.

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Brain Anatomy Review • Cerebellum – Coordination of voluntary muscle movement. – Equilibrium and posture.

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Brain Anatomy Review • Brain Stem: – – –

Connects hemispheres, cerebellum and spinal cord. Responsible for vegetative functions and VS. Midbrain is the relay point for visual and auditory impulses. – Pons is the conduction pathway between brain and other regions of body. – Medulla oblongata • cardiac, respiratory, and vasomotor control centers. • control of vomiting and coughing.

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Brain Anatomy Review • Brain Stem: – Origin of the 12 Cranial Nerves. – Reticular Activating System. • Level of arousal (level of consciousness).

– Meninges: • Dura mater. The tough outer layer, separates cerebellum from cerebral structures, landmark for lesions. • Arachnoid. The web-like middle layer that contains venous vessels that reabsorb CSF. • Pia mater. Directly attached to brain tissue. 26

Meninges • • •

Dura Mater Arachnoid Pia Mater

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Brain Anatomy Review • Brain Stem – Cerebral Spinal Fluid (CSF) • • • • •

Produced by the cells of the choroid plexus. Clear, colorless, oily liquid. Circulates through brain and spinal cord. Cushions, cleans, and protects. Ventricles: – – –

Located in the center of brain. Secrete CSF by filtering blood. Cells of the ventricles form the blood-brain barrier.

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Brain Metabolism & Perfusion • High metabolic rate. – – – – –

Receives 15% of total cardiac output. Consumes 20% of body’s oxygen. 25% of glucose utilization (largest user). Requires thiamine. Cannot store nutrients.

• Blood Supply – Vertebral arteries supply posterior brain (cerebellum and brain stem). – Carotid arteries supply most of cerebrum.

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Brain Metabolism & Perfusion • Perfusion – Cerebral Blood Flow (CBF) • Dependent upon CPP. • Flow requires pressure gradient.

– Cerebral Perfusion Pressure (CPP) • Pressure moving the blood through the cranium. • Autoregulation allows BP change to maintain CPP. • CPP = Mean Arterial Pressure (MAP) - Intracranial Pressure (ICP).

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Brain Metabolism & Perfusion • Perfusion – Mean Arterial Pressure (MAP) • Largely dependent on cerebral vascular resistance (CVR) since diastolic is main component. • Blood volume and myocardial contractility. • MAP =[(2 x diastolic) + systolic] / 3 . • Usually requires MAP of at least 60 mmHg to perfuse brain (50 – 70 mmHg).

– Intracranial Pressure (ICP) • Increases with edema or hemorrhage. • ICP usually 10-15 mm Hg.

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Brain Injury By definition:

“a traumatic insult to the brain capable of producing physical, intellectual, emotional, social and vocational changes”

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Brain Injury • Three broad categories: – Focal injury • • •

Cerebral contusion Intracranial hemorrhage Epidural hemorrhage

– Subarachnoid/subdural hemorrhage – Diffuse Axonal Injury • Concussion (mild and classic form) 42

Any patient with head or facial injuries, has a cervical spine injury until proven otherwise.

4/30/2009

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Brain Injury • Direct primary brain injury results from: – External forces applied to outside of skull transmitted to the brain. – Mechanical disruption of cells. – Movement of brain inside skull. – Vascular disruption or permeability causing cerebral hypoxia. 44

Brain Injury • Indirect (secondary or tertiary) brain injury may be due to: – Secondary • Edema, hemorrhage, infection, inadequate perfusion, tissue hypoxia, pressure.

– Tertiary • Apnea, hypotension, pulmonary resistance, ECG changes.

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Intracranial Pressure (ICP) • ICP is usually low (